Can't e-mail Pages text file
I'm trying to send a 500 page manuscript in Pages to an editor, but she can't open the file -- instead she gets a message reading: "The required index xml file is missing." I'm running Pages 8.0 (6194). I've never had a problem sending Pages files before. The answers to somewhat similar questions here are six years old, so maybe they don't apply. Any ideas?
MacBook Pro 13″, macOS 12.7